1. Field of the Invention
The present invention relates to an optical information recording medium that records information with a special recording apparatus and reproduces the information with an existing reproducing apparatus.
2. Description of the Related Art
A compact disc recordable (so-called CD-R) includes a light-transmissive substrate with a diameter of 12 cm and a thickness of 1.2 mm and a surface provided with a spiral groove for guiding an optical head and recording information. On the surface having the groove, a recording layer and a reflection layer are disposed in this order. This groove is provided with a wobble meandering at a predetermined cycle along the running direction for detecting exact location information. This groove is also called a track. The cross section in the running direction of the groove has a trapezoidal shape having an upper portion broadly opened and a bottom with a slightly narrowed width. In general, data is recorded on and/or reproduced from the recording layer by irradiating the substrate with laser light having a wavelength of about 780 nm from the other side of the substrate. A digital versatile disc recordable (so-called DVD-R) includes a light-transmissive substrate with a diameter of 12 cm and a thickness of 0.6 mm and a surface provided with a spiral groove, as in above, having a wobble meandering at a pitch smaller than the half of the cycle of the CD-R. A recording layer and a reflection layer are disposed in this order on the surface having the groove, and a dummy substrate with a diameter of 12 cm and a thickness of 0.6 mm is further pasted thereon. In general, data is recorded on and/or reproduced from the recording layer by irradiating the substrate with laser light having a wavelength of about 630 to 680 nm from the other side of the substrate.
Optical information recording media such as CD-Rs and DVD-Rs are capable of recording and reproducing large amounts of digital data relatively inexpensively and are thereby widely used. However, since it is easy to copy data recorded in these optical information recording media, there is a concern that illegally copied products, such as music CDs and videos, may appear on the market. In addition, recently, data of images and music are distributed online, and, therefore, a system for protecting copyright is required.
As described in Japanese Unexamined Patent Application Publication No. 2002-157740, many companies provide various systems for protecting copyright. Furthermore, optical information recording media that record data with a special recording apparatus, but reproduce the data with a general reproducing apparatus, have been developed in recent years. In such optical information recording media, recording of data is impossible without the special recording apparatus, which is very effective for preventing illegal copy.
In the optical information recording medium that records data with a special recording apparatus, the recorded data is read out without problems using a general reproduction-only apparatus, such as a DVD reproducing apparatus. However, a general recording/reproducing apparatus, such as a recording drive of a personal computer or a DVD recorder, may not read out the data due to an error.
Such a general recording/reproducing apparatus includes a system that detects the class of an optical information recording medium. This procedure is also applied to an optical information recording medium provided with an anti-illegal copy measure. In this case, the general recording/reproducing apparatus does not recognize the optical information recording medium provided with an anti-illegal copy measure as a read only memory (i.e., ROM), but recognizes it instead as a recordable optical information recording medium. However, since a general recording apparatus is not capable of recording data on this optical information recording medium provided with an anti-illegal copy measure, a read-out error occurs. As a result, a problem of not reading out the recorded data is caused.